being a common Cat Bird in which the haemapophysis had disappeared from the first dorsal rib, the true ribs being thus reduced to five in number. It is quite possible that reduction in the dorsal region has been carried almost to its utmost extent among birds and existing facts seem to support this theory. Among the highly specialized Passeres, the normal number of ribs, counting as the first the most anterior that is connected with the sternum, is uniformly gix. Close to the Passeres stands the heterogeneous group of birds termed Picariæ, many of which are doubtless survivals of the ancient forms from which the Passeres have been derived. If this be the case the line of descent of these Picarians is a long one and in many respects they may have undergone more modification than their more recent relatives. Certain it is that in this group we find, with very few exceptions, those birds having the smallest number of ribs, sometimes only five pairs, and at least once, in our Night Hawk, only four. In the Swifts, near relatives of the Goatsuckers, it is not asserting too much to say that we can actually see the process of rib reduction going forward, for among these birds we find many specimens with six pairs of ribs, rarely one with seven, and in the majority of cases six complete pairs of ribs and the lower portion of a seventh, and this lower rudiment is present in varying proportions. Lower in the scale, among the Amphibians, the number of vertebræ is inconstant, even in such species as Necturus and Menopoma, whose pre-sarial vertebræ are fewer in number than in any mammal. Necturus may have eighteen or nineteen pre-sacrals, Menopoma nineteen or twenty, Siren forty-one, forty-two or forty-three, and Amphiuma sixty-four or sixty-five. Variation in the number of caudals is, of course, to be expected, but in the long-bodied Siren and Amphiuma it may amount to as many as five or six vertebræ. A curious variant has been noted in the sacrum of Menopoma, which Huxley, in the last edition of the Encyclopædia Britannica, describes and figures as composed of two vertebræ. Unfortunately the specimen on which the figure and description are based was abnormal, for, like the Salamanders, Menopoma has normally but one sacral, and an intermediate condition, a true abnormality, may exist of ten vertebræ connected with the ilium on one side and one on the other. It is evident from the instances just related that a considerable amount of individual variation in size, proportion of various bones, or even in the presence of certain bones, may exist in a given species. Differences of size, unless excessive, are of little value, provided the parts retain their relative proportions and in judging of differences of proportion the question of age must be taken into account also. Broadly speaking, variations are of two kinds, due to modifications of development or of structure, and the importance of any departure from a given type depends very largely on the answer to the question, to which of these two categories does the variation belong. Modifications of development produce individual variations of size and strength, length of limb and power of jaw, modifications of structure-when constant-give rise to specific, generic or ordinal distinctions, as the case may be. In the occasional extra molar of the Orang the extra ribs of birds, the tarsal tubercle of the Great Auk, and the varying number of vertibræ in Amphibians we have variations of structure that, being inconstant, have no specific value, and yet have a morphologic meaning of their own. The extra molar of the Orang is probably a reversionary character, the extra ribs of the Auk and the little nodule occupying the place of the missing metatarsal certainly indicate an ancestral form with a longer body and four toes. In the abnormal sacrum of the Menopoma and the five pairs of ribs of the Cat Bird we have progressive variations, and these are of much rarer occurrance than retrogressive characters. The parapophyses in the sacral vertebræ of Cormorants are teleological modifications, efforts to provide an additional brace for the pelvic walls of these strong swimmers. The differences in the axial skeleton of birds and Amphibians indicate that variation in this region is not greatest in animals now possessing the largest number of vertebral segments, but in those whose embryology hints at the existence of more vertebræ in their comparatively immediate ancestors than are possessed by the descendants of these forms. This would account for the frequent appearance of extra ribs in birds, the inconstancy of the number of vertebral segments in Urodele Amphibians, and the constancy in the vertebral column of mammals. To conclude, many variations are reversionary in character. some progressive, and some due to physiological causes, most, if not all, have some definite meaning in their abnormality. NOTES ON JAPANESE METEOROLOGY. BY ALBERT S. ASHMEAD, M.D., NEW YORK, NY. DESPITE the humid climate of Japan, rheumatism is very rare among the natives, which is probably due to the practice of daily hot bathing. The meteorology of Japan is exceedingly peculiar and of exceptional interest. As particular influences in the process of acclimatization may be mentioned, lessened, eliminatory activity of the lungs, increased activity of the skin, diminished cardial circulatory power. A prolonged residence in the Japanese climate is productive of general physical relaxation, with increased susceptibility to cold. After a two years' residence in Japan, Europeans feel the necessity of wearing more substantial winter clothing, as the climate seems to have become harsher since the beginning of their sojourn. Any foreigner who permanently resides there and wishes to feel at ease must resort to the hot bathing of the natives; being in Japan, he must do as Japanese do. Europeans, on their first arrival, are very prone to rheumatism, and even perfected acclimatization does not do away with that propensity. The hot-bath habit is singularly favorable to perfect acclimatization; it, and also the customary and frequent hot tea, mitigates the depressive influence of the summer kakké months, the wet season of June, July, and August. Strange to say, in their national disease, beriberi, there is an entire absence of perspiration; these patien's perspire only in their last agony. One should think, after that, that the Japanese would consider baths as remedial in kakké. Strange to say, it is not so; they consider it only as an essential and, for them, very pleasant part of the toilet. In kakké the popular verdict is, and has always been, that it is detrimental. The altitudinal is their most efficient treatment. Such a treatment is always, at least in our European and American experience, a dry one; dry air. It is not so in Japan; in their mountains, even as high as 3,000 feet above the sea level, you will find an increase of humidity, due to the precipitation from the volcanic peaks. Even in this heavy humidity, where they are endeavoring to cure a disease in which perspiration is suppressed, they do not give to the hot baths which are used there as much, but not more than in other not sanitary places, credit for any good accruing to the patients. And, in fact, if hot bathing contributed to the cure, such an influence would be observed at the sea-level as well as in high altitudes. Let me Of course, I cannot treat the question expressed here. only say that, in my opinion, humidity has nothing to do, directly at least, with beriberi; it is not a climatic rheumatism. Its cause is the action of a carbonic poison in the blood, and that poison cannot be eliminated through the influence of hot water. Hot bathing, as I said, has nothing to do with it, either directly or indirectly. Indirectly humidity has, because it keeps the carbonic gases together and prevents their dispersion. The oxydizing influence of the pure air of the mountain heights has everything to do with the cure. LETTERS TO THE EDITOR. Correspondents are requested to be as brief as possible. The writer's nume is in all cases required as proof of good faith. On request in advance, one hundred copies of the number containing his communication will be furnished free to any correspondent. The editor will be glad to publish any queries consonant with the character of the journal. Bibliographic Work in Vegetable Physiology. I AM on the point of making a suggestion to students of botany, chemistry, and more specially of physiology. I would be glad to receive notes concerning the literature of any question in physiology, in order to use them in my bibliographical work concerning the physiology of plants. Under the head-title of "Contributions from the Missouri Botanical Garden" a series of bibliographical papers will be published, treating of every question within the range of vegetable physiology. Students of any college in the country could assist me a great deal, if they would inform me of their being willing to pick up occasional notes on this or that question. The bibliographies of Inuline, and of the Tannoids, both with special reference to the rôle played by these constituents in vegetable physiology, have already been issued. The question taken up at present is that of the alcoholic fermentation. Anybody wishing to assist the writer in preparing his bibliography on this subject by sending lists of references - all of which will be welcome- or by looking through a journal or other periodical, thus saving a little time for the writer, without much loss of time for himself, will receive hearty thanks, and will be mentioned as a contributor. This note being submitted to the attention of all students of science as well as professional scientific men, I wish that students of colleges and universities would act upon it. Often students are at a loss as to how to do scientific work and contribute to general knowledge. Here is one of the departments where much work is needed. References might be taken in the following way: 1. Select some chemical, botanical, or physiological journal. Begin with Vol. I., and go over the whole series carefully, noticing every place where the alcoholic fermentation has in any way been mentioned. 2. Write carefully: (a) Title of the paper, (b) name of the journal (for journals, see Bolton's Catalogue of Scientific and Technical Periodicals, 1665-1882, and his Catalogue of Chemical Periodicals, the first is found in any library, and was published by the Smithsonian Institution; the latter is found in the annals of the New York Academy of Sciences, Vol. III., Nos. 6-7, pp. 161-216, 1885, with supplement, ibidem, Vol. IV., pp. 19-22, 1887), (c) volume, page, and year. 3. Examine text-books and handbooks in which the question of the alcoholic fermentation is mentioned. 4. Examine also papers and works which do not bear directly upon this matter; sometimes interesting remarks may be found. J. CHRISTIAN BAY. Missouri Bot. Garden, St. Louis, Mo., July 18, 1893 A Plea for Botany in the Small Colleges. The many pleas made for a better presentation of botany in the larger institutions of the country, have induced me to add a word for botany in the smaller colleges. The present status of the science in these institutions is indeed discouraging as it is presented in their catalogues. The traditional term of botany given by an instructor in physics or chemistry is the common allowance doled out to the students. The conditions are, however, changing gradually, and chairs of biology are being established in many of the smaller colleges, whose incumbents are occasionally botanists. As a teacher of botany in one of these colleges, the writer wishes to add a plea for the introduction of botany in its proper proportion into the college curriculum. The character of the work of the college is somewhat different from that of the university in that its courses are necessarily briefer and less specialized. Their students more frequently Pennsylvania Bedford Springs Mineral Water For Liver, Kidney and Bladder Troubles. For Dyspepsia, Rheumatism and Gout. It has been used medicinally and prescribed by physicians for nearly one hundred years. DIRECTIONS:-Take one or two glasses about a half-hour before each meal. Case One Dozen Half-Gallon Bottles, $4.50. Bedford Mineral Springs Co., Bedford, Pa. Ex-President Andrew D. prevalent in all ranks of society. In the MINERALS. White, of Cornell University, says: "I believe thatthe highest interests of Christian civilization and of humanity would be served by its adoption." "So set down, our tongue is the best for the world to unite upon."-Brooklyn Eagle. "The idea of Mr. Bell has much to recommend it, and the presentation is charmingly clear."-Ameri can, Phila. "The result is a language which cannot fail to meet with acceptance."-Boston Traveller. "World English deserves the careful consideration of all serious scholars."-Modern Language Notes. Sent, postpaid, on receipt of price. first part of this work the author dwells on causes of the malady. The allegory forming By CYRIL BENNETT. N. D. C. HODGES, 874 Broadway, N. Y. N. D. C. HODGES, 874 Broadway, New York. $5 to $15 per day, at home, selling LIGHTNING PLATER and plating jewelry, watches tableware, &c. Plates the finest of jewelry good as new, on all kinds of metal with gold, silver or nickel. No experience. No capital. Every house has goods needing plating. Wholesale to agents $5. Write for circulars. H. E. DELNO & Co., Columbus, 0. New Store. New Stock. New Departments. Minerals, Gems, Microscopical Sections, Fine LapSend for our "Winter Bulletin," recently issued. idary Work. GEO. L. ENGLISH & CO., Mineralogists, Removed to 64 East 12th Street, New York THE CHEAPEST AND BEST! PHOTO ENGRAVING 6. 67 PARK PLACE, NEW YORK ENGRAVING FOR ALL ILLUSTRATIVE AND pursue a course which leads to the so-called general education, and the question naturally arises, what place has botany in such a scheme of equipment for life? To the average college graduate few if any of the sciences can be said to be directly useful, they profit him largely in the breadth of view which they give, and the pleasure they are able to furnish in their contemplation or pursuit. In these latter respects one can scarcely conceive of a science which would rank higher than botany. There are certainly no phenomena which are met with more frequently by the non-professional than those which appertain to plants and plant life. Without becoming sentimental one may say with truth that to one who has an intimate knowledge of this field of nature the world around us takes on a new aspect, and new truths can be discovered and added daily to the fund already acquired. But it is on account of the peculiar adaptability of botany to teaching, that the science should appeal to the smaller institutions. That science is best adapted to teaching which is able to present its material at first hand for investigation, and whose truths are within the ability of the student to discover. The material for botanical study is abundant everywhere, and presents problems in a measure peculiar to each region. The early stages of investigation in the science are not difficult and do not require expensive apparatus. The live teacher who sends his students to the field and not to books, will find in botany a science in which enthusiasm can be aroused and progress made without an expensive outfit. In the planning of our college courses in botany one must needs bear in mind two classes of students, those who are to go on with the science and those who pursue it as one of the elements of a general education. It is the former class who too frequently suffer in the average college. The courses should be given in such a manner as to give the student who wishes to pursue the science in a university a foundation which does not need repeating because it is antiquated or Delicious Drink. abbreviated. In this way I believe the small colleges can be made centres of enthusiasm for botanical science, which will materially advance its teaching and its standing in this country. It is to be hoped that botany will one day take its place in the curriculum of the small college as one of its most important constituents for the training of men. X. AMONG THE PUBLISHERS. "CAMP-FIRES of a Naturalist" is the title of a forthcoming book which sketches big-game hunting in the west from a fresh point of view. The author describes the actual adventures and experiences of a naturalist, Professor Dyche, of Kansas University, who has hunted from Mexico to the northern confines of British Columbia, pursuing grizzly bears, mountain sheep, elk, moose and other rare game. As an outdoor book of camping and hunting this possesses a timely interest, but it also has the merit of scientific exactness in the descriptions of the habits, peculiarities and haunts of wild animals. The author is Mr. Clarence E. Edwards, and the book is to be published immediately by D. Appleton & Co., with many illustrations. -Professor Charles S. Minot's "Human Embryology" is announced to be translated into German. The translation is being made by Dr. S. Kæstner and will be published by Messrs. Veit of Leipzig. The author has revised the entire work for the German edition and has made a series of changes and additions, which will render the translation practically a new edition. Among the changes is the making of a new chapter in the Introduction, giving a complete account of the external development and growth of the human embryo through all stages. References have also been added to important papers published since the original American edition was issued. The honor of a German translation has hitherto been accorded very rarely to American scientific works. Exchanges. [Free of charge to all, if of satisfactory character. A complete set of Bulletins of U. S. Geological Horsford's Acid Phosphate Chamberlin, fe logist, ted, consists of four with water and sugar only, makes a delicious, healthful and invigorating drink. Allays the thirst, aids digestion, and relieves the lassitude so common in midsummer. Dr. M. H. Henry, New York, says: "When completely tired out by prolonged wakefulness and overwork, it is For sale or exchange.-A complete set of the report of the last Geological Survey of Wisconsin, large volumes, finely illustrated, and upwards forty large maps and charts. Will sell for cash or Address Geo. Beck, Platteville, Wis. exchange for a microscope. For sale or exchange for copper coins or rare postage stamps. Tryon's American Marine Conchology, containing hand colored figures of all the shells of the Atlantic coast of the United States. Presentation copy, autograph, etc. One vol., half morocco, 8vo, usual price, $25, postpaid, $15. Botany of the Fortieth Parallel of the Hundredth Meridian of the Pacific R. R. Survey. Other Botanical works and works on Ethnology. F. A. Hassler, M.D., Santa Ana, Cal. I have a fire-proof safe, weight 1,150 pounds, which I will sell cheap or exchange for a gasoline suit. The safe is nearly new, used a short time engine or some other things that may happen to only. Make offers. A. Lagerstrom, Cannon Falls, Minn., Box 857. mission will hold examinations on August 15 to RAFTSMEN WANTED.-The Civil Service Comfill two vacancies in the War Department; one in the position of architectural draftsman, salary $1,400, the other in the position of assistant draftsman, Quartermaster General's office, salary $1,200. The subjects of the architectural draftsman examination are letter-writing, designing specifications and mensuration, and knowledge of materials; of the assistant draftsman examination they are letter-writing, tracing, topographic drawing and projections. The examination will be held in arrangements may be made for examinations in the Washington, and if applications are filed in season, large cities. Blanks will be furnished upon application to the Commission at Washington. A YOUNG man who has been through the course in mathematics in Princeton University, wishes some tutoring this summer. Rates reasonable. Address P. H Westcott, Cramer's Hill, Camden Co., N. J. For exchange.-Hudson River fossils in good condition from the vicinity of Moore's Hill, Ind., also of the greatest value to me. As a bev-land and fresh water shells. Desire fossils and shells from other groups and localities. Address erage it possesses charms beyond any- Geo. C. Hubbard, Moore's Hill, Ind. A GRADUATE of an American Polytechnic institution and of a German university (Göttingen), thing I know of in the form of medi-graphic camera, rosewood box, one foot square, similar institution. For sale at low price.-A fine old-fashioned photo-seeks a position to teach chemistry in a college or fenses, four inches diameter, made by C. C. Harri- teaching chemistry, Address Chemist, 757 Cary St., Five years' experience in cine." son. Plateholders, troughs, baths, etc., all in large Brockton, Mass. wooden case, formerly the property of the late President Moore, of Columbia College. This is a fine example of an instrument of the best make for Rumford Chemical Works, Providence, R. I. the old wet-process methods, and valuable to any institution of amateur interested in the history of Beware of Substitutes and Imitations. photography in the U. S. Address M. S. Daniel, 236 W. 4th St., New York. Descriptive pamphlet free. experienced teacher in general biology wishes a position in a first-class college or university. Three years in post-graduate study. Extensive experience. Strong indorsements. Address E. W. Doran, Ph.D., 1327 G St., N. W., Washington, D. C. I wish to exchange a collection of 7.000 sheus seminary in central New York. Typewriting. 1001 species and varieties, American and foreign, HREE teachers wanted for a male and female etc., languages, mathematics, sciences, et. al. Send stamp with and for particulars. Box 701, Hempstead, L. I. THE American Bell Telephone COMPANY. 125 MILK ST., BOSTON, MASS. This Company owns the Letters - Patent No. 186,787, granted to Alexander Graham Bell, January 30th, 1877, the scope of which has been defined by the Supreme Court of the United States in the following terms: "The patent itself is for the mechanical structure of an electric telephone to be used to produce the electrical action on which the LIGHTNING DESTROYS! Shall it be your house or a pound of copper? Entirely new departure in pro tecting buildings from lightning. QUERY. Can any reader of Science cite a case of lightning stroke in which the dissipation of a small conductor (one-sixteenth of an inch in diameter, say,) has failed One hundred feet of the Hodges to protect between two horizonPatent Lightning Dispeller tal planes passing through its (made under patents of N. D. C. upper and lower ends respective first patent rests. The third claim is for the Hodges, Editor of Science) will use in such instruments of a diaphragm, made of a plate of iron or steel, or other ma terial capable of inductive action; the fifth, be sent, prepaid, to any ad of a permanent magnet constructed as de scribed with a coil upon the end or ends dress, on receipt of five dollars. nearest the plate; the sixth, of a sounding box as described; the seventh, of a speaking or hearing tube as described for conveying the sounds; and the eighth, of a permanent magnet and plate combined. The claim is not for these several things in and of them Correspondence solicited. Agents wanted. ly? Plenty of cases have been found which show that when the conductor is dissipated the building is not injured to the extent explained (for many of these see volumes of Philosophical Trans selves, but for an electric telephone in the AMERICAN LIGHTNING PROTECTION CO., actions at the time when light construction of which these things or any of them are used." This Company also owns Letters-Patent No. 463,569, granted to Emile Berliner, No 874 Broadway, New York City. ning was attracting the attention of the Royal Society), but not vember 17, 1891, for a combined Telegraph Fact and Theory Papers an exception is yet known, al and Telephone, and controls Letters-Patent No. 474,231, granted to Thomas A. Edison, May 3, 1892, for a Speaking Telegraph, I. THE SUPPRESSION OF CON- BUSINESS OPPORTUNITY. There is an opening for a young man to open a New York office of the American Lightning Protection Co., operating under my patents. But little capital will be required. N. D. C. HODGES, 874 BROADWAY, NEW YORK INDEX TO VOLUME XVIII OF SCIENCE is in preparation, and will be issued at an early date. N. D. C. HODGES, 874 Broadway, New York, N. Y. SUMPTION. By GODFREY W. HAMBLETON, M.D. 12°. 40c. II. THE SOCIETY AND THE "FAD." C. F. Cox. 12°. 75 cents. though this query has been published far and wide among electricians. First inserted June 19, 1891. No response to date. IV. THE CHEROKEES IN PRE-CON. D. C. HODGES, 874 BROADWAY, N. Y. CAL CULTURE CHART, with illustrated directions for developing every part of the body healthfully, 50 cts. Sent for half price to those naming this paper. WHITNEY HOME GYMNASIUM CO., Box D., Rochester, N. Y. SCIENCE ELEVENTH YEAR. VOL. XXII. No. 548. CONTENTS. THE FLORIDA LAND TORTOISE-GOPHER, GOPHERUS 57 58 59 A NEW IDEA IN MICROSCOPE CONSTRUCTION. C. W. Woodworth... SUMMER WORK IN MARINE ZOOLOGY AT NEWPORT. 59 60 60 AUGUST 4, 1893. NEO-DARWINISM AND NEO-LAMARCKISM. By LESTER F. WARD. Annual address of the President of the Biological Society of Washington delivered Jan. 24, 1891. A historical and critical review of modern scientific thought relative to heredity, and especially to the problem of the transmission of acquired characters. The following are the several heads involved in the discussion Status of the Problem, Lamarckism. Darwinism, Acquired Characters, Theories of Heredity, Views of Mr. Galton, Teachings of Profes 30r 63 Weismann, A Critique of Weismann, Neo-DarwinOBSERVATIONS ON DUCKLINGS. C. Lloyd Morgan. 63 ism, Neo-Lamarckism, the American "School," Ap NOTES AND NEWS.. 61 61 ..... รุง +61 9. GLE COPIES, TEN CENTS. USEFUL HAND The Ornamental Penman's Pocketbook of Alphabets, for sign-writers, engravers, stone-cutters and draftsmen, 20 cts. A System of Easy Lettering, by Howard Cromwell, 50 cts. Practical Electrics: A Universal Handybook on Every-day Electrical Matters, 135 pp., fully illustrated, 12mo, cloth, 75 cts. Notes on Design of Small Dynamo, by G. Halliday, 79 pp., with a number of plates to scale, 12mo, cloth, $1. The Phonograph and How to Construct It, by W. Gillett, 87 pp., 12 folding plates, 12mo, cloth, $2. SPON & CHAMBERLAIN, Publishers, 12'Cortlandt St., New York. Illustrated and descriptive catalogues, 10 cts. The Batrachians and Reptiles of Indiana. A Work of 204 pages, with 3 plates of 12 figures Contains full descriptions of nearly one hundred species of Batrachians and Reptiles, together with abundant notes on their habits. The identification of the species made easy by means of analytical tables. By O. P. Hay, Ph.D. Price, in paper cover, postpaid, $1.00. Bowen-Merrill Book Co, Indianapolis, Ind. GERMANIA A monthly magazine for the study of the German language and literature, is highly recommended by college professors and the press as "the best effort yet made to assist the student of German, and to interest him in his pursuit." Its BEGINNERS' CORNER furnishes every year a complete and interesting course in German Box 151, Manchester, N. H. N. D. C. HODGES, 874 Broadway, New York. grammar, $2 a year. Single copies 20 cents. P. O. NEW METHOD OF PROTECTING BUILDINGS FROM LIGHTNING. SPARE THE ROD AND SPOIL THE HOUSE! Lightning Destroys. Shall it be Your House or a Pound of Copper? PROTECTION FROM LIGHTNING. What is the Problem? IN seeking a means of protection from lightning-discharges, we have in view two objects,-the one the prevention of damage to buildings, and the other the prevention of injury to life. In order to destroy a building in whole or in part, it is necessary that work should be done; that is, as physicists express it, energy is required. Just before the lightning-discharge takes place, the energy capable of doing the damage which we seek to prevent exists in the column of air extending from the cloud to the earth in some form that makes it capable of appearing as what we call electricity. We will therefore call it electrical energy. What this electrical energy is, it is not necessary for us to consider in this place; but that it exists there can be no doubt, as it manifests itself in the destruction of buildings. The problem that we have to deal with, therefore, is the conversion of this energy into some other form, and the accomplishment of this in such a way as shall result in the least injury to property and life. Why Have the Old Rods Failed? When lightning-rods were first proposed, the science of energetics was entirely undeveloped; that is to say, in the middle of the last century scientific men had not come to recognize the fact that the different forms of energyheat, electricity, mechanical power, etc.- were convertible one into the other, and that each could produce just so much of each of the other forms, and no more. The doctrine of the conservation and correlation of energy was first clearly worked out in the early part of this century. There were, however, some facts known in regard to electricity a hundred and forty years ago; and among these were the attracting power of points for an electric spark, and the conducting power of metals. Lightning-rods were therefore introduced with the idea that the electricity existing in the lightning-discharge could be conveyed around the building which it was proposed to protect, and that the building would thus be saved. The question as to dissipation of the energy involved was entirely ignored, naturally; and from that time to this, in spite of the best endeavors of those interested, lightning-rods constructed in accordance with Franklin's principle have not furnished satisfactory protection. The reason for this is apparent when it is considered that the electrical energy existing in the atmosphere before the discharge, or, more exactly, in the column of dielectric from the cloud to the earth, above referred to, reaches its maximum value on the surface of the conductors that chance to be within the column of dielectric; so that the greatest display of energy will be on the surface of the very lightningrods that were meant to protect, and damage results, as so often proves to be the case. It will be understood, of course, that this display of energy on the surface of the old lightning-rods is aided by their being more or less insulated from the earth, but in any event the very existence of such a mass of metal as an old lightning-rod can only tend to produce a disastrous dissipation of electrical energy upon its surface,-"to draw the lightning," as it is so commonly put. Is there a Better Means of Protection? Having cleared our minds, therefore, of any idea of conducting electricity, and keeping clearly in view the fact that in providing protection against lightning we must furnish some means by which the electrical energy may be harmlessly dissipated, the question arises, "Can an improved form be given to the rod so that it shall aid in this dissipation?" As the electrical energy involved manifests itself on the surface of conductors, the improved rod should be metallic; but, instead of making a large rod, suppose that we make it comparatively small in size, so that the total amount of metal running from the top of the house to some point a little below the foundations shall not exceed one pound. Suppose, again, that we introduce numerous insulating Joints in this rod. We shall then have a rod that experience shows will be readily destroyed-will be readily dissipated - when a discharge takes place; and it will be evident, that, so far as the electrical energy is consumed in doing this, there will be the less to do other damage. The only point that remains to be proved as to the utility of such a rod is to show that the dissipation of such a conductor does not tend to injure other bodles in its immediate vicinity. On this point I can only say that I have found no case where such a conductor (for instance, a bell wire) has been dissipated, even if resting against a plastered wall, where there has been any material damage done to surrounding objects. Of course, it is readily understood that such an explosion cannot take place in a confined space without the rupture of the walls (the wire cannot be boarded over); but in every case that I have found recorded this dissipation takes place just as gunpowder burns when spread on a board. The objects against which the conductor rests may be stained, but they are not shattered, I would therefore make clear this distinction between the action of electrical energy when dissipated on the surface of a large conductor and when dissipated on the surface of a comparatively small or easily dissipated conductor. When dissipated on the surface of a large conductor, a conductor so strong as to resist the explosive effect, - damage results to objects around. When dissipated on the surface of a small conductor, the conductor goes, but the other objects around are saved A Typical Case of the Action of a Small Conductor. Franklin, in a letter to Collinson read before the London Royal Society, Dec. 18, 1755, describing the partial destruction by lightning of a church-tower at Newbury, Mass, wrote, "Near the bell was fixed an iron hammer to strike the hours; and from the tall of the hammer a wire went down through a small gimlet-hole in the floor that the bell stood upon, and through a second floor in like manner; then horizontally under and near the plastered ceiling of that second floor, till it came near a plastered wall; then down by the side of that wall to a clock, which stood about twenty feet below the bell. The wire was not bigger than a common knitting needle. The spire was split all to pieces by the lightning, and the parts flung in all directions over the square in which the church stood, so that nothing remained above the bell. The lightning passed between the hammer and the clock in the above-mentioned wire without hurting either of the floors, or having any effect upon them (except making the gimlet-holes, through which the wire passed, a little bigger), and without hurting the plastered wall, or any part of the building, so far as the aforesaid wire and the pendulum-wire of the clock extended; which latter wire was about the thickness of a goose-quill. From the end of the pendulum, down quite to the ground, the building was exceedingly rent and damaged. . . . No part of the aforementioned long, small wire, between the clock and the hammer, could be found, except about two inches that hung to the tail of the hammer, and about as much that was fastened to the clock; the rest being exploded, and its particles dissipated in smoke and air, as gunpowder is by common fire, and had only left a black smutty track on the plastering, three or four inches broad, darkest in the middle, and fainter towards the edges, all along the ceiling, under which it passed, and down the wall." One hundred feet of the Hodges Patent Lightning Dispeller (made under patents of N. D. C. Hodges, Editor of Science) will be mailed, postpaid, to any address, on receipt of five dollars ($5). Correspondence solicited. Agents wanted. AMERICAN LIGHTNING PROTECTION CO., 874 Broadway, New York City. |